JP2019523350A - Composite carbon fiber - Google Patents

Abstract

Composite carbon fibers having carbon fibers electrografted with an amine functionalized polymer on the surface are provided. Electrografting an amine functionalized polymer onto the surface of a carbon fiber results in a composite carbon fiber in which the polymer is covalently bonded to the fiber and a significant number of reactive amine groups are present in the fiber reinforced composite. It can be used for subsequent reactions in the production of the material, for example to react with a resin matrix. As a result, composite carbon fibers can be particularly useful in the production of fiber reinforced composite materials that exhibit improved interlayer strength. A fiber reinforced composite material is also provided.

Description

  The present invention relates generally to carbon fibers for use in making fiber reinforced composite materials, and in particular to composite carbon fibers comprising carbon fibers that have been electrografted with an amine functionalized polymer on the surface.

  Fiber reinforced composite materials are increasingly being used in a wide variety of applications due to their relatively light weight and high strength. An example of such an application is the aviation industry where there is a desire to improve fuel efficiency by reducing airframe weight. The fiber reinforced composite structure provides a material that has a lower density than the corresponding structure, including alloys, while retaining mechanical properties comparable to steel and aluminum.

  In general, fiber reinforced composite materials include a resin matrix that is reinforced with fibers such as carbon fibers. The fiber-reinforced composite material is usually produced by a method in which a cloth or tow containing fibers is impregnated with a resin to form a so-called prepreg. The term prepreg is often used to describe a reinforced composite material comprising fibers impregnated with a resin and in an uncured or partially cured state. The prepreg can then be molded into a final or semi-final molded part by exposing the prepreg to conditions sufficient to cure the resin. Typically, curing is performed by heating the prepreg in a mold for a sufficient time at a temperature sufficient to cure the resin. Epoxy resins are often used in the manufacture of fiber reinforced composite materials.

  The adhesion of the carbon fibers to the resin matrix is extremely important to maintain the mechanical strength of the part and prevent delamination at the fiber-carbon interface. In order to improve adhesion, carbon fibers are usually treated by surface treatment before impregnation with resin. A common surface treatment method involves passing carbon fibers through an electrochemical or electrolytic cell containing a solution such as ammonium hydrogen carbonate, and applying an electrical potential, resulting in anodization of the carbon fiber surface. Such treatment etches or roughens the surface of each filament to increase the surface area available for interfacial fiber / matrix bonding. The increase in fiber surface area assists in mechanical engagement of the resin matrix with the fibers. Furthermore, the surface treatment can also oxidize the fiber surface, resulting in the formation of reactive chemical groups such as carboxylic acids on the fiber surface.

  However, there are several drawbacks that can be associated with surface treatment. For example, in some situations, surface treatment can result in undesirable degradation of the fiber, resulting in a practical limit on the amount of surface treatment that can be provided with carbon fiber. As a result, the surface treatment may not provide sufficient levels of reactive chemical groups on the surface of the fiber.

  Accordingly, there remains a need for improved carbon fibers and methods for making them.

  Embodiments of the present invention relate to amine functionalized carbon fibers and methods of making amine functionalized carbon fibers. A further aspect of the present invention relates to a reinforced composite material comprising a resin matrix and an amine functionalized fiber and a method for producing such a reinforced composite material.

  In one embodiment, aspects of the invention relate to composite carbon fibers that include carbon fibers that are electrografted with an amine functionalized polymer on a surface. The inventors have discovered that fiber grafted composites with improved interlayer properties can be made by electrografting an amine functionalized polymer onto the carbon fiber surface.

  Embodiments of the present invention can provide composite carbon fibers comprising carbon fibers that are electrografted with an amine functionalized polymer on the surface. In one embodiment, the composite carbon fiber has a nitrogen / carbon (N / C) ratio of at least 0.125, in particular an N / C ratio of about 0.15-0.3, and even more particularly about 0.00. It has an N / C ratio that is 15-0.2. In one embodiment, the composite carbon fiber has an N / C ratio that is at least 0.150, such as an N / C ratio that is about 0.15 to 0.3.

  In one embodiment, the composite carbon fiber is at least 50%, at least 75%, at least 100%, at least 125% compared to the original carbon fiber that has not been electrografted with an amine functionalized polymer on the surface of the carbon fiber. , At least 150%, at least 175%, at least 200% or at least 250%. In one particular embodiment, the composite carbon fiber exhibits an increase in nitrogen surface concentration that is at least 495% compared to the original carbon fiber where the amine functionalized polymer is not electrografted onto the surface of the carbon fiber.

  In some embodiments, the composite carbon fiber has an increase in nitrogen surface concentration that is about 50-500% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface of the carbon fiber. Show. For example, in one embodiment, the composite carbon fiber exhibits an increase in nitrogen surface concentration of about 100-500% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface of the carbon fiber. obtain. In other embodiments, the composite carbon fiber exhibits an increase in nitrogen surface concentration that is about 150-500% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface of the carbon fiber. . In yet another embodiment, the composite carbon fiber is about 100-250%, such as about 125-200% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface of the carbon fiber. An increase in nitrogen surface concentration may be shown.

  In one embodiment, the amine functionalized polymer is a linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, poly Selected from the group consisting of branched poly (allylamine) (PAADVB) and block copolymers, core-shell particles and combinations thereof prepared by branching (allylamine) with divinylbenzene. In a preferred embodiment, the amine functionalized polymer comprises branched polyethyleneimine.

  Preferably, the amine functionalized polymer has a weight average molecular weight in the range of about 5,000 to 35,000.

  A wide variety of different carbon fibers can be used in accordance with the present invention. In one embodiment, the carbon fibers can have a tensile strength of at least 400 ksi. For example, carbon fibers for making composite carbon fibers can have a tensile strength of about 600 to 1,050 ksi.

  The composite carbon fibers according to the present invention can be used to make a wide variety of different articles. For example, composite carbon fibers can be used to make fiber reinforced composite materials, such as prepregs, or structural elements formed from prepregs.

  In one embodiment, the present invention may provide a fiber reinforced composite comprising carbon fibers electrografted with an amine functionalized polymer on a surface and a resin matrix injected into the carbon fibers. In one such embodiment, the fiber reinforced composite material may exhibit an interlaminar strength of about 17-25 ksi, as characterized by a Short Beam Shear (SBS) test. In some embodiments, the interlaminar strength of the fiber reinforced composite is about 20-22 ksi, as characterized by SBS.

  In one embodiment, the present invention is in the range of about 5-25% compared to similar fiber reinforced composites in which the carbon fibers are identical except that the surface of the carbon fibers does not contain an amine functionalized polymer. Fiber reinforced composite materials can be provided that exhibit an increase in SBS up to.

  In one embodiment, the fiber reinforced composite material may include a resin selected from the group consisting of an epoxy resin, a bismaleimide resin, a cyanate ester resin, and a phenol resin.

  In one embodiment, the composite carbon fiber for making the fiber reinforced composite material is at least 25%, at least 50%, at least compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. 75%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200%, at least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375% , At least 400%, at least 425%, at least 450%, at least 475%, or at least 500% of any one or more increases in nitrogen concentration at the surface. In some embodiments, the composite carbon fiber for use in the fiber reinforced composite material is about 50-3,000% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface. May show an increase in the surface of the nitrogen concentration ranging from, for example, about 100-500%, about 150-500%, about 100-250%, or about 125-200%.

  In one embodiment, fiber reinforced composite materials according to embodiments of the present invention can be used in the manufacture of aerospace components.

  Another aspect of the invention is a composite carbon fiber comprising carbon fibers electrografted with an amine functionalized polymer on the surface, wherein the composite carbon fibers are characterized by the following:

  a) a nitrogen / carbon (N / C) ratio of at least 0.125, and / or

b) Increase in nitrogen surface concentration which is about 50-500% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface of the carbon fiber.
In such embodiments, the composite carbon fiber is about 0.15-0.3, such as about 0.15-0, compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. .2 and a nitrogen / carbon (N / C) ratio of about 0.165 to 0.195 and at least 75%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200%, at least 225% Any one or more of: at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, at least 450%, at least 475%, or at least 500% Can show an increase in the nitrogen concentration at the surface.

  In one embodiment, the composite carbon fiber according to the previous paragraph is about 50-3,000%, such as about 100-500%, compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface, An increase in the surface of the nitrogen concentration can range from about 150-500%, about 100-250%, or about 125-200%.

  In another aspect, an embodiment of the present invention is a method of preparing a composite carbon fiber comprising:

  Passing carbon fibers through a bath containing an amine functionalized polymer;

  Applying a potential to the cell;

  Electrolytically grafting an amine functionalized polymer on carbon fiber to produce composite carbon fiber having an electrofunctionalized amine functionalized polymer on the surface, wherein the composite carbon fiber is characterized by:

  a) a carbon / nitrogen (N / C) ratio of at least 0.125, and / or

  b) Increase in nitrogen surface concentration which is about 50-500% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface of the carbon fiber.

  In one aspect of the method, the composite carbon fiber has a nitrogen / carbon (N / C) ratio of about 0.15 to 0.3, such as about 0.15 to 0.2 and about 0.165 to 0.195. Indicates.

  In another aspect of the method, the composite carbon fiber is at least 75%, at least 100%, at least 125%, at least 150% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. At least 175%, at least 200%, at least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, at least 450%, at least It shows an increase in the surface of one or more nitrogen concentrations of either 475% or at least 500%.

  In one embodiment of the method of making the composite carbon fiber, the composite carbon fiber is about 50-3,000%, such as about 50% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface. An increase in the surface of the nitrogen concentration ranging from 100-500%, about 150-500%, about 100-250% or about 125-200% may be shown.

  In one embodiment of the method of making the composite carbon fiber, the amine functionalized polymer is a linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), Polyamidoamine (PAMAM) dendrimers, selected from the group consisting of branched poly (allylamine) (PAADVB) prepared by branching poly (allylamine) with divinylbenzene and combinations thereof. In a preferred embodiment, the amine functionalized polymer comprises branched polyethyleneimine.

  In one embodiment, the amine functionalized polymer has a weight average molecular weight ranging from about 5,000 to 35,000.

  Advantageously, the step of electrografting the amine functionalized polymer onto the surface of the carbon fiber can be completed in a relatively short time. For example, in one embodiment, the step of electrografting the amine functionalized polymer onto the carbon fiber may require a period that lasts 30 seconds to 2 minutes, particularly 45 seconds to 90 seconds, and particularly about 60 seconds. .

  Embodiments of the invention can be directed to composite carbon fibers and molded parts made therefrom. The invention also includes a method of making a composite carbon fiber and a method of making a fiber reinforced composite material including the composite carbon fiber.

  Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale.

1 is a schematic diagram of a mechanism for electrografting an amine functionalized polymer onto carbon fiber. FIG.

  The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

  Terms such as “first”, “second”, “primary”, “exemplary”, “secondary” do not imply order, quantity or importance, but rather one element Used to distinguish from elements. Further, the terms “a”, “an”, and “the” do not imply a limit on the amount, but rather indicate the presence of “at least one” of the items mentioned.

  Each embodiment disclosed in this specification is considered to be applicable to each of the other disclosed embodiments. All combinations and subcombinations of the various elements described herein are within the scope of the invention.

  Where a parameter range is given, it is understood that all integers within that range, as well as their percents and minutes, are also given by the present invention. For example, “5-10%” includes 5%, 6%, 7%, 8%, 9% and 10%, 5.0%, 5.1%, 5.2%,... 9.8% , 9.9% and 10.0% and 5.00%, 5.01%, 5.02% ... 9.98%, 9.99% and 10.00%.

  As used herein, “about” in the context of a numerical value or range means ± 10% of the numerical value or range listed or claimed.

  In one aspect, embodiments of the present invention provide composite carbon fibers comprising carbon fibers electrografted with an amine functionalized polymer on a surface. As described in more detail below, electrografting an amine functionalized polymer onto the surface of a carbon fiber results in a composite carbon fiber in which the polymer is covalently bonded to the fiber and a significant number of Reactive amine groups are available for subsequent reactions in the production of fiber reinforced composites, for example to react with a resin matrix. As a result, composite carbon fibers can be particularly useful in the production of fiber reinforced composite materials that exhibit improved interlayer strength.

  The composite carbon fibers according to the present invention can be used in a wide variety of applications where a fiber reinforced composite material having high interlaminar strength is desired, as characterized by the Short Beam Shear (SBS) test. Although composite carbon fibers can be used alone, the composite carbon fibers are generally combined with a resin to form a fiber reinforced composite material. The fiber reinforced composite material may be in the form of a prepreg or cured final part. While fiber reinforced composite materials can be used for any intended purpose, fiber reinforced composite materials are preferably used in aerospace applications for both structural and non-structural components.

  For example, composite carbon fibers can be used to form fiber reinforced composite materials used in aircraft structural components such as fuselage, wing and tail assemblies. Composite carbon fibers can also be used to produce composite parts used in non-structural parts of aircraft. Exemplary non-structural exterior components include engine nacelles and aircraft skins. Exemplary interior parts include aircraft kitchen and washroom structures, as well as window frames, floor panels, overhead storage, wall dividers, wardrobes, ducts, ceiling panels, and internal sidewalls.

  As noted above, composite carbon fibers provide a number of reactive amine groups that are available for subsequent reactions. The presence of available reactive amine groups in the composite carbon fiber can be characterized by the carbon / nitrogen (N / C) ratio of the composite carbon fiber. For example, composite carbon fibers according to the present invention typically exhibit a nitrogen / carbon (N / C) ratio of at least 0.125, more typically an N / C ratio of at least 0.150. In one embodiment, the composite carbon fiber has an N / C ratio that is about 0.15-0.3, such as about 0.15-0.2 and about 0.165-0.195. In some embodiments, the composite carbon may have an N / C ratio that is at least 0.120, such as from 0.120 to 0.200. The N / C ratio of the composite carbon fiber can be determined using analytical methods known in the art such as X-ray photoelectron spectroscopy (XPS).

  Composite carbon fibers according to embodiments of the present invention are compared to the same carbon fibers that are not electrografted with an amine functionalized polymer on the surface (eg compared to the original carbon fiber before electrografting the amine functionalized polymer). And may also show an increase in surface nitrogen concentration. For example, composite carbon fibers according to embodiments of the present invention may exhibit an increase in nitrogen surface concentration of at least 25% compared to identical carbon fibers that are not electrografted with an amine functionalized polymer on the surface.

  More particularly, the composite carbon fiber is at least 25%, at least 50%, at least 75%, at least 100%, at least 125 compared to the same carbon fiber that is not electrografted with an amine functionalized polymer on the surface. %, At least 150%, at least 175%, at least 200%, at least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, It can show an increase in nitrogen surface concentration of at least 450%, at least 475% and at least 500%.

  In one embodiment, the composite carbon fiber may exhibit an increase in nitrogen surface concentration in the range of about 50-5,000% compared to the same carbon fiber where the amine functionalized polymer is not electrografted on the surface. . Preferably, the composite carbon fiber is about 50-500%, more preferably about 100-500%, even more preferably about 50% compared to the same carbon fiber where the amine-functionalized polymer is not electrografted on the surface. Shows an increase in nitrogen surface concentration ranging from 150-500%. In other embodiments, the composite carbon fiber is about 100 to 250%, more typically about 125 to 200%, compared to the same carbon fiber where the amine functionalized polymer is not electrografted on the surface, Even more typically, it may show an increase in nitrogen surface concentration ranging from about 150 to 200%. The surface nitrogen concentration of the composite carbon fiber can also be measured using analytical methods known in the art such as X-ray photoelectron spectroscopy (XPS).

  Furthermore, fiber reinforced composite materials made from composite carbon fibers can exhibit improved interlayer strength. In one embodiment, a fiber reinforced composite material according to an embodiment of the present invention is a similar fiber reinforced composite in which the carbon fibers are identical except that the surface of the carbon fibers has not been modified to include an amine functionalized polymer. Compared to the material (hereinafter referred to as “non-grafted carbon fiber”), it may show an increase in SBS ranging from about 5 to 25%. Preferably, the fiber reinforced composite material exhibits an increase in SBS ranging from about 7 to 25%, more preferably from about 10 to 25%, compared to a composite material comprising non-grafted carbon fibers. In one embodiment, the fiber reinforced composite material may exhibit an increase in SBS in the range of about 15-25% compared to a composite material comprising non-grafted carbon fibers.

  In one embodiment, fiber reinforced composite materials prepared from composite carbon fibers exhibit an interlaminar strength of about 17-25 ksi, particularly about 18-24 ksi, more specifically about 20-22 ksi as characterized by SBS. .

  Composite carbon fibers according to aspects of the present invention can be prepared by immersing the carbon fibers in a bath solution containing an amine functionalized polymer. The bath can be aqueous or non-aqueous and can contain one or more electrolytes.

  Examples of suitable non-aqueous solvents may include methanol, ethanol, dimethylformamide, dimethyl sulfoxide, sulfolane, tetrahydrofuran and acetonitrile, among others.

  Examples of suitable electrolytes include, among others, tetraethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, tetraethylammonium hexafluorophosphate, tetrabutylammonium hexafluorophosphate, tetrabutylphosphonium hexafluorophosphate, tetraethylammonium Perchlorate, tetrabutylammonium perchlorate, tetraethylammonium trifluoromethanesulfonate, tetrabutylammonium trifluoromethanesulfonate, lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium triflate, lithium bis ( Trifluoromethanesulfonyl) imide and lithium bis (trif Is Oro ethanesulfonyl) imide may be mentioned.

  The concentration of the electrolyte in the bath can range from about 0.01 to 1M with respect to the total volume of the electrolyte solution in the bath. In one embodiment, the amount of electrolyte in the bath is about 0.01-0.5M, especially about 0.015-0.1M, more particularly about 0.02-0.05M.

  The concentration of amine functionalized polymer in the bath can range from about 0.5 to 5% by weight relative to the total weight of the bath. In one embodiment, the amount of amine functionalized polymer in the bath is about 0.5-2.5 wt%, especially about 0.75-2 wt%, more particularly about 1.0-2.0 wt%. %.

  As shown in FIG. 1, the mechanism for electrografting an amine functionalized polymer onto carbon fibers is represented by reference numeral 10. The mechanism 10 includes an electrolytic cell 12, a power source 14, a cathode 16 and a carbon fiber 18. The power supply 14 is connected to the cathode (s) 16 via a conductor 20 and is connected to the carbon fiber 18 via a conductor 22. The mechanism can also include one or more Teflon-coated pulleys with carbon fibers oriented thereon. This mechanism may also include a pump (not shown) for recirculating the bath solution. After the carbon fibers are drawn through the bath, they are directed to a washing station (washing machine) 30 where the fibers are rinsed with deionized water. The composite fiber can then pass through dryer 32 and be wound on take-up spooler 34 for later use. In some embodiments, the cell can also include a reference electrode 24 connected to a voltmeter (eg, digital multimeter) 28 that can then be connected to the cathode 16 via a conductor 26.

  The carbon fibers can be exposed to the bath over a period of about 30 seconds to 5 minutes. Advantageously, it has been found that amine functionalized polymers can be electrografted onto carbon fibers with exposure times ranging from about 1 to 2 minutes, in particular about 1 minute.

  The applied voltage typically ranges from about 0.1 to 10 volts, with a voltage of about 0.5 to 5 volts being preferred.

  In embodiments of the present invention, a wide variety of amine functionalized polymers can be used. Preferably, the amine-functionalized polymer is available for electrografting to the carbon fiber surface or is available for subsequent reaction with the resin matrix and is distributed along the main chain or branch of the polymer. Containing amine groups. For example, in a preferred embodiment, the amine functionalized polymer comprises a plurality of pendant amino groups, terminal primary amino groups, secondary amino groups, tertiary amino groups or mixtures thereof incorporated into the polymer structure.

In one embodiment, the amine functionalized polymer comprises a polymer of formula (I) and (II).

  In formulas (I) and (II), the R groups can independently represent hydrogen, straight chain, branched, cyclic or alkyl groups (saturated or unsaturated), aliphatic groups, aromatic groups or mixtures thereof. In some embodiments, R can include ethoxylated segments, heterocyclic compounds, and heteroatoms in addition to the groups described above.

  In some embodiments, R is an amine protecting group such as carbobenzyloxy, methoxybenzylcarbonyl, tert-butyloxycarbonyl, 9-fluorenylmethyloxycarbonyl, acetyl, benzoyl, benzyl, carbamate, methoxybenzyl, 3 , 4-dimethoxybenzyl, p-methoxyphenyl, tosyl and sulfonamide may also be included.

  In preferred embodiments, the amine-functionalized polymer comprises a carbon (eg, organic) based polymer backbone, such a backbone comprising a hydrocarbon-based moiety that can be aromatic or aliphatic (saturated or unsaturated). Such backbones can be linked through C—C bonds, C—O bonds, C—N bonds, C—S bonds, and N—N bonds. In some embodiments, the backbone can include hydrocarbon moieties that incorporate heteroatoms such as O, N, S. The aforementioned part can also be a heterocyclic part. In other embodiments, the backbone of the amine functionalized polymer can be derived from a siloxane-based polymer. The main chain may be cross-linked or substantially free of cross-linking.

  In general, it may be desirable for the amine functionalized polymer to have a weight average molecular weight (Mw) of greater than about 2,000, in particular greater than about 2,500. Although there is no general practical limit to the Mw of the amine functionalized polymer, the polymer can have a Mw ranging from about 5,000 to 1,000,000, and about 15,000 to 750,000. Mw ranging in the range is somewhat more typical, and Mw ranging from about 15,000 to 100,000 is more typical. As is known in the art, the Mw of a polymer can be determined using static light scattering techniques.

  In one embodiment, the amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine and linear poly (allylamine) (PAA), poly (allylamine) with divinylbenzene. Selected from branched poly (allylamine) (PAADVB) prepared by branching and mixtures thereof. In a preferred embodiment, the amine functionalized polymer is a branched polyethyleneimine.

  In one embodiment, the amino functionalized polymer can comprise a copolymer. For example, an amine functionalized polymer can include a polymer structure derived from a mixture of monomers that contain amine functional groups and monomers that do not. Examples of such copolymers include block copolymers and core-shell particles derived from such copolymers. Block copolymers (see, for example, US Pat. No. 6,894,113) and core-shell particles (see, for example, European Patent Application Publication No. 1632533A1, US Patent Application Publication No. 2008 / 0251203A1, European Patent Application Publication No. No. 2123711A, European Patent Application Publication No. 2135909A1 and European Patent Application Publication No. 2256163A1) are widely described in the literature as reinforcing additives to epoxy resins. One of the most interesting and relevant examples of such copolymers and core-shell particles described in the literature by Berg et al. (Nguyen, F .; Saks, A .; Berg, JCJ. Adhesion Sci.Technol.2007, 21, pp.1375-1393; Leonard, GC; Hosseinpour, D.; Berg, JCJ Adhesion Sci.Technol. 2009, 23, pp.2031-2046. Where the outer shell consists of polyethyleneimine polymerized onto polystyrene core particles.

  In one embodiment, the amine functionalized polymer can have a polysiloxane polymer backbone. One example of such a polymer can be found in WO 2004/035675 A1, which the author has described for the preparation of sol-gel particles having amine functional groups on the surface and having a crosslinked polysiloxane structure as the core. it can.

In one embodiment, the amine functionalized polymer can comprise a polyamidoamine (PAMAM) dendrimer. PAMAM dendrimers are hyperbranched polymers that typically include an ethylenediamine core, a repetitively branched amidoamine internal structure, and a primary amine surface. Dendrimers grow from the central core in an iterative process where each step has approximately twice as many reactive surface sites as the previous generation and generates a new generation of dendrimers with approximately twice the molecular weight. Examples of generation 0 and generation 1 of PAMAM dendrimers are shown below.

  In yet another embodiment, the amine functionalized polymer may comprise a highly branched polyamidoamine described by Buchman et al. (Dodiuk-Kenig, H .; Buchman, A .; Kenig, S. Composite Interfaces 2004, 11, pp. 453-469 and references therein). Therein, the synthesis of highly branched amine functional polymers is based on the amine-epoxy reaction.

  In some embodiments, the amine functionalized polymer can include block copolymers and core-shell particles. For example, in one embodiment, the amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine and linear poly (allylamine) (PAA), poly (allylamine) divinyl. It may include block copolymers and core-shell particles of branched poly (allylamine) (PAADVB) and combinations thereof prepared by branching with benzene.

  A wide variety of different carbon fibers can be used in accordance with embodiments of the present invention. In one embodiment, the carbon fibers are considered aerospace grade carbon and may have a tensile strength of at least 400 ksi (2,758 MPa). The carbon fiber may have at least one tensile strength of, for example, 450 ksi, 500 ksi, 550 ksi, 600, ksi, 650 ksi, 700 ksi, 750 ksi, 800 ksi, 850 ksi, 900 ksi, 950 ksi or 1,000 ksi. In one embodiment, the carbon fibers may have a tensile strength of about 400 to 1200 ksi, particularly about 600 to 1,050 ksi, more particularly about 700 to 950 ksi.

  Preferably, the carbon fiber is disposed on the tow. “Tow” (sometimes called “roving” or simply “fiber”) is a multifilament fiber. The number of filaments per tow can be, for example, 100 to 30,000. The tow should be thermally and chemically stable under prepreg formation (eg, curing of the matrix resin composition).

  Typically, the fibers have a circular or substantially circular cross section with a diameter in the range of 0.5-30 microns, preferably 2-20 microns, more preferably 2-15 microns. In terms of weight, individual tows can have a weight of, for example, 200 to 3,000 g / 1000 meters, 600 to 2,000 g / 1000 meters, or 750 to 1750 g / 1000 meters. In a preferred embodiment, individual tows can have a weight of 200-500 g / 1,000 meters.

  In some embodiments, the carbon fibers can be surface treated prior to electrografting the amine functionalized polymer onto the fibers. In other embodiments, the carbon fibers can be untreated prior to electrografting. Preferably, the carbon fibers are not subjected to any treatment that can reduce the tensile strength of the fibers prior to electrolytic grafting. For example, in various embodiments, the carbon fibers are not subjected to a high temperature treatment in a steam atmosphere, such as a temperature above 800 ° C., or a plasma treatment.

  In some embodiments, it may be desirable for the fibers to be unsized, or at least de-sized, prior to bonding of the amine functionalized polymer to the carbon fibers. In one embodiment, the composite carbon fiber can be used as either sized or removed by a formulation known to those skilled in the art, depending on the application.

  Examples of suitable carbon fibers include HEXTOW® AS-4, AS-7, IM-7, IM-8, IM-9 and IM-10 and HM-63 carbon fibers, all of which PAN continuous fiber available from Hexel (Dublin, Calif.). IM-7 to IM-10 are high performance, medium elastic continuous PAN based carbons available as 12,000 (12K) filament number tows with minimum tensile strengths of 820 ksi, 880 ksi, 890 ksi and 1,010 ksi respectively. Fiber.

  Carbon fibers from other carbon manufacturers can also be used in some embodiments of the present invention. For example, in some embodiments, suitable carbon fibers include Aksaca 3K A-38, 6K A-38, 12K A-42, 24K available from Dow Aksa Ileri Kompozit Malzemeler Saai Ltd, Sti, Istanbul, Turkey. A-42, 12K A-49 and 24K A-49 carbon fibers may be mentioned. These product names are the approximate number of thousands of filaments / rovings (eg 3K is 3,000 filaments) and the approximate tensile strength of fibers of several hundred MPa (A-38 is a tensile of 3,800 MPa) Indicating strength). Other carbon fibers that can be used in accordance with embodiments of the present invention are believed to include T700 and T800, available from Toray Industries, Inc.

  Composite carbon fibers according to embodiments of the present invention can be used in a wide variety of reinforcing structures. For example, the composite fibers can be arranged to form a unidirectional, bi-directional or multi-directional reinforcing structure depending on the desired properties required for the final reinforced composite material. The composite carbon fibers can be in the form of tows or fabrics, and can be in the form of random, knitted, non-woven, polyaxial (eg, non-crimped fabric), braided or any other suitable pattern.

When unidirectional fiber layers are used, the orientation of the bicomponent fibers can be the same or can vary throughout the prepreg stack to form a so-called non-crimp fabric (NCF). However, this is only one of many orientations that can be considered in a stack of unidirectional fiber layers. For example, unidirectional fibers in adjacent layers can be arranged orthogonal to each other in a so-called 0/90 arrangement that indicates the angle between adjacent fiber layers. Of course, other arrangements such as 0 / + 45 / −45 / 90 are possible, among many other arrangements. In one embodiment, carbon fibers, 150~2,000g / ^{m 2,} may in particular comprise a braided fabric or non-crimp fabric having a basis weight of 300~1600g / ^{m 2.}

  The prepreg according to the embodiment of the present invention can be manufactured by injecting a resin composition such as an epoxy resin into carbon fiber or a cloth containing carbon fiber.

  A wide variety of different resin compositions may be used in the practice of the present invention. Preferably, the resin composition includes a crosslinkable thermosetting system. Suitable examples of thermosetting resins include epoxy resins, bismaleimide resins, cyanate ester resins, and phenol resins. An example of a suitable bismaleimide (BMI) resin that can be used in the present invention is available from Hexel under the trade name HEXPLY®.

  In some embodiments, the resin composition may include a thermoplastic resin. Examples of suitable thermoplastic resins include polyaryl ether ketones (PAEK) such as polyether ether ketone (PEEK) and polyether ketone ketone (PEKK), polyamides such as nylon, polyphenylene sulfide (PPS), polyetherimide ( Mention may be made of PEI), polyphenylene oxide (PPO), polyethersulfone (PES), polybenzimidazole (PBI) and polycarbonate (PC).

  In one embodiment, the resin composition may include an epoxy resin composition. Typically, the resin composition may include 55 to 75 weight percent of an epoxy resin component that includes one or more epoxy resins. The epoxy resin can be selected from any epoxy resin used in high performance aerospace epoxies. Bifunctional, trifunctional and tetrafunctional epoxy resins can be used. In one embodiment, the epoxy resin can consist essentially of a trifunctional epoxy compound. If desired, a tetrafunctional epoxy can be included. The relative amounts of trifunctional and tetrafunctional epoxies may be varied as is known to those skilled in the art.

  A trifunctional epoxy resin is understood to have three epoxy groups that are substituted directly or indirectly in a para or meta orientation on the phenyl ring in the main chain of the compound. A tetrafunctional epoxy resin is understood to have four epoxy groups in the main chain of the compound. Examples of suitable substituents include hydrogen, hydroxyl group, alkyl group, alkenyl group, alkynyl group, alkoxyl group, aryl group, aryloxy group, aralkyloxy group, aralkyl group, halo group, nitro group or cyano group. It is done. Suitable non-epoxy substituents can be attached to the phenyl ring at the para or ortho position, or can be attached at the meta position not occupied by an epoxy group.

  Examples of suitable trifunctional epoxy resins include phenol and cresol epoxy novolac, glycidyl ether of phenol-aldehyde adduct, aromatic epoxy resin, dialiphatic triglycidyl ether, aliphatic polyglycidyl ether, epoxidized olefin, bromine Resins comprising aromatic resins, aromatic glycidyl amines and glycidyl ethers, heterocyclic glycidyl imidines and amides, glycidyl ethers, fluorinated epoxy resins or any combination thereof. A preferred trifunctional epoxy is the triglycidyl ether of paraaminophenol, which is commercially available as Araldite MY 0500 or MY 0510 from Huntsman Advanced Materials (Montery, Switzerland). A particularly preferred trifunctional epoxy is triglycidyl ether of meta-aminophenol, which is trade name Araldite MY0600 from Huntsman Advanced Materials (Monter, Switzerland) and trade name ELM from Sumitomo Chemical Co., Ltd. (Osaka, Japan). -120 commercially available.

  Examples of suitable tetrafunctional epoxy resins include phenol and cresol epoxy novolaks, glycidyl ethers of phenol-aldehyde adducts, aromatic epoxy resins, dialiphatic triglycidyl ethers, aliphatic polyglycidyl ethers, epoxidized olefins, bromines Resins comprising aromatic resins, aromatic glycidyl amines and glycidyl ethers, heterocyclic glycidyl imidines and amides, glycidyl ethers, fluorinated epoxy resins or any combination thereof. A preferred tetrafunctional epoxy is N, N, N ', N'-tetraglycidylmethylenedianiline, which is commercially available from Huntsman Advanced Materials (Monter, Switzerland) as Araldite MY0720 or MY0721.

  If desired, the epoxy resin component may also include a bifunctional epoxy, such as bisphenol A (bis A) or bisphenol F (bis F) epoxy resin.

Examples of suitable epoxy resins include diglycidyl ethers of polyhydric phenol compounds such as resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1,1-bis (4-hydroxyphenyl) -1-phenylethane) Diglycidyl ethers of bisphenol F, bisphenol K, bisphenol M, tetramethylbiphenol; diglycidyl ethers of aliphatic glycols and polyether glycols, such as C _2-24 alkylene glycols and poly (ethylene oxide) or poly (propylene oxide) glycols Diglycidyl ether; phenol-formaldehyde novolac resin, alkyl-substituted phenol-formaldehyde resin (epoxy novolac resin), phenol-hyd Mention may be made of droxybenzaldehyde resins, cresol-hydroxybenzaldehyde resins, dicyclopentadiene-phenolic resins and polyglycidyl ethers of dicyclopentadiene-substituted phenolic resins; and any combination thereof.

  Suitable diglycidyl ethers include, for example, D.I. E. R. (Registered trademark) 330 resin, D.I. E. R. (Registered trademark) 331 resin, D.I. E. R. (Registered trademark) 332 resin, D.I. E. R. (Registered trademark) 383 resin; E. R. (Registered trademark) 661 resin and D.I. E. R. (Registered trademark) 662 resin and diglycidyl ether of bisphenol A resin sold as Araldite GY6010 (Huntsman Advanced Materials). Exemplary bis-F epoxy resins are commercially available as Araldite GY281 and GY285 (Huntsman Advanced Materials).

  Commercially available diglycidyl ethers of polyglycol include D.C. E. R. (Registered trademark) 732 and D.I. E. R. What is marketed as (registered trademark) 736 is mentioned.

  Epoxy novolac resins can also be used. Such resins are available from Dow Chemical Company as D.I. E. N. (Registered trademark) 354, D.I. E. N. (Registered trademark) 431, D.I. E. N. (Registered trademark) 438 and D.I. E. N. (Registered trademark) 439 is commercially available.

  The epoxy resin component can optionally include 5-20% by weight of a thermoplastic toughening agent. It is well known that thermoplastic toughening agents are used to make high performance epoxy resins. Exemplary toughening agents include polyethersulfone (PES), polyetherimide (PEI), polyamide (PA) and polyamideimide (PAI). PES is commercially available from various chemical manufacturers. As an example, PES is available from Sumitomo Chemical Co., Ltd. (Osaka, Japan) under the trade name Sumika Excel 5003p. Polyetherimide is commercially available from Sabic (Dubai) as ULTEM 1000P. Polyamideimide is commercially available as TORLON 4000TF from Solvay Advanced Polymers (Alpharetta, GA). The thermoplastic component is preferably supplied as a powder that is mixed with the epoxy resin component prior to the addition of the curing agent.

  The epoxy resin composition may also include additional components such as performance enhancers and / or modifiers. The performance enhancer or modifier may be selected from, for example, softeners, particulate fillers, nanoparticles, core / shell rubber particles, flame retardants, wetting agents, pigments / dyes, conductive particles and viscosity modifiers.

  In some embodiments, the injecting step can be performed at an elevated temperature such that the viscosity of the resin composition is further reduced. However, it should not be so hot for a sufficient time that an undesirable level of curing of the resin composition occurs.

  In a preferred embodiment of the present invention, the injection / impregnation of the resin composition into the carbon fibers is performed at a temperature sufficient for the resin to flow within and between the fibers. For example, the injection temperature of the resin composition may be in the range of 100 to 200 ° C, in the range of 120 to 180 ° C, and more preferably about 150 ° C. It should be appreciated that temperature ranges outside the above ranges can also be used. However, the use of higher or lower injection temperatures typically requires adjustment of the machine speed at which the injection process takes place. For example, at temperatures above about 175 ° C., it is necessary to perform the injection process at a higher mechanical speed to reduce the period of time the resin composition is exposed to high temperatures and avoid unwanted crosslinking of the resin composition. It can be.

  Similarly, lower machine speeds are typically required to inject the epoxy resin composition into the fiber material when using a lower injection temperature to obtain the desired level of injection and thereby reduce voids in the prepreg. It becomes.

  Typically, the resin composition is applied to the carbon fiber at a temperature in this range and is consolidated into the fiber, for example by pressure applied by passing through one or more pairs of nip rollers.

  A further aspect of the invention relates to a method for preparing a prepreg according to an embodiment of the invention. In the first step, the epoxy resin composition is extruded onto a sheet material to form a thin film coating thereon. The sheet material includes a release film or paper from which the film coating of the epoxy resin composition can be transferred to the fiber material during the prepreg processing step. After depositing a film of the epoxy resin composition on the sheet material, the sheet material having a film coating can be passed over a chill roll to cool the epoxy resin composition. The sheet material is then typically wound on a roll for future use.

Example

  Test method

  X-ray photoelectron spectroscopy (XPS)

  The XPS analysis of the carbon fiber sample was carried out with an apparatus PHI 5701LSci equipped with a monochromated Al kα 1486.6 eV X-ray source with an acceptance angle of ± 7 ° and an extraction angle of 50 °. The analysis area was 2 mm × 0.8 mm. The obtained value was normalized to 100% using the detected element. Trace elements were not reported.

  Test samples were prepared by cutting a 20 cm sample from the spool followed by sonication in a solvent for 30 minutes. After 15 minutes, the solvent was changed to a new one. Fiber samples were dried overnight at 80 ° C. under reduced pressure.

  Tensile strength

  The tensile strength of the carbon fiber sample was measured according to the procedure described in ASTM D-4018.

  Short beam shear (SBS)

  In order to evaluate the interlaminar strength of fiber reinforced composites using SBS according to ASTM D 2344, various laminated panels were made. The sample width was 0.25 ± 0.005 inches. A span to depth ratio of 4: 1 was used. Nine replicates were tested for each sample.

Laminated panel samples were made using either BMI or epoxy resin. The BMI-injected laminate had a basis weight of 190 g / m ² and was made by laying 12 layers of carbon fibers. The epoxy injection laminate had a basis weight of 145 g / m ² and was made by laying 16 layers of carbon fibers. Carbon fiber was laid by hand or using a tension stand. All layers had a 0 ° orientation and were laid on BMI or epoxy tape. The panel was then cut and pressed to form a prepreg. The length of the carbon fiber was about 30 meters. The laminated panel was cured according to the following.

  The epoxy injected laminated panel was cured using two cycles in an autoclave.

  1) Curing cycle: The laminated panel was heated to 240 ° F. and held at 65 PSI for 65 minutes. The panel was then heated to 350 ° F. and held at a pressure of 100 PSI for 120 minutes. The panel was then cooled to 140 ° F. at a rate of 3 ° F. per minute.

  2) Post cure cycle: The panel was then heated to 350 ° F. and held at this temperature for 4 hours. The panel was then cooled to 140 ° F.

  The BMI injection laminate was similarly cured in an autoclave using two cycles.

  1) Curing cycle: The laminated panel was heated to 250 ° F. and held at a pressure of 85 PSI for 30 minutes. The panel was then heated to 375 ° F. and held at this temperature at a pressure of 85 PSI for 250 minutes. The panel was cooled to 140 ° F. at a rate of 3 ° F. per minute.

  2) Post cure cycle: The panel was then heated to 465 ° F. and held for 6 hours 30 minutes. The panel was then cooled to 140 ° F.

  The material used for the adhesive composition is shown below. Unless otherwise noted, all percentages are percentages by weight. Unless otherwise stated, all physical properties and composition values are approximate.

  “B-PEI-1” refers to a branched polyethyleneimine available from Sigma-Aldrich® (having an average Mw of about 25,000 and an average Mn of about 10,000).

  “B-PEI-2” refers to branched polyethyleneimine (having an average Mw of about 800 and an average Mn of about 600) available from Sigma-Aldrich®.

  “L-PEI” refers to linear polyethyleneimine available from Polysciences (having an average Mw of about 2,500).

  “PAA” refers to poly (allylamine) polyethyleneimine (having an average Mw of about 15,000) available from Polysciences.

  “TAEA” refers to tris (2-aminoethyl) amine (96%) available from Sigma-Aldrich®.

  “TEABF” refers to tetraethylammonium tetrafluoroborate (99%) available from Sigma-Aldrich®.

  “MEOH” refers to methanol (anhydrous) available from Sigma-Aldrich®.

“Na ₂ SO ₄ ” indicates sodium sulfate (99.0% or more, ACS reagent grade, anhydrous) available from Sigma-Aldrich (registered trademark).

  "IM-7" is a 100% nominal surface treated PAN-based continuous carbon fiber (12,000 (12K) filament number tow with a minimum tensile strength of 820 ksi) available from Hexel under the trade name HEXTOW®. Indicates. The carbon fiber was not sized.

  “IM-X” indicates 5% nominal surface-treated PAN-based continuous carbon fiber (12,000 (12K) filament number toe with a minimum tensile strength of 825 ksi) made by Hexel. The carbon fiber was not sized.

  “IM-U” indicates a surface-untreated PAN-based continuous carbon fiber (12,000 (12K) filament number tow) manufactured by Hexel. The carbon fiber was not sized.

  “BMI” refers to a bismaleimide resin available from Hexel under the name HX1624.

  “Epoxy” (“EPOXY”) refers to a proprietary epoxy resin available from Hexel.

  A composite carbon fiber was produced according to the following procedure.

  An amine functionalized polymer was electrografted onto the surface of the carbon fiber using a bath similar to that shown in FIG. The power source used in the electrolytic grafting process was a DC power source 1030 manufactured by BK Precision. A carbon cathode was used in this step. The cathode had a generally elongated rectangular shape and was supplied by Americancarb (grade AX-50). The dimensions of the cathode were 21 cm × 2.5 cm × 1.2 cm. The experiment used either a non-aqueous Ag / Ag + reference electrode or an aqueous Ag / AgCl reference electrode. A non-aqueous Ag / Ag + reference electrode (CHI 112) was purchased from CH Instruments, Austin, Texas and was filled with 10 mM silver nitrate and 20 mM supporting electrolyte solution in an organic solvent. An aqueous Ag / AgCl reference electrode (CHI 112) was purchased from the same supplier and filled with a 1M KCl solution.

  Carbon fiber tow was fed from a controlled tension feed spooler onto a steel roller. A steel roller was connected to the positive end of the power supply. A carbon cathode was immersed in the vessel and connected to the negative end of the power source. Carbon fiber tow was fed onto a Teflon coated roller located at the bottom of the tank and then passed over a second steel roller outside the tank. The carbon fibers were then washed with deionized water, dried and then wound on a take-up spool.

  The applied voltage was adjusted so that the potential read by the silver reference electrode placed very close to the carbon fiber tow was about 1.6 volts. The distance between the cathodes was 2.5 cm and the fiber travel path length was 61 cm (2 feet). The bath solution was recirculated by a peristaltic pump and replenished as necessary to maintain a constant volume. The carbon fiber bath exposure time was varied between 1 and 4 minutes depending on the experimental trial.

  The tank volume was about 1 liter. The wash tank used deionized water and included a multi-path and multi-roller mechanism with a total water volume of about 2 liters. The wash tank was purged and completely replaced with fresh deionized water every 30 minutes. The dryer was a drying tower using hot air at 125 ° C.

In the examples below, the difference in simple adsorption of an amine functionalized polymer (B-PEI-1) compared to an electrograft of the same polymer was evaluated. Electrolytic grafting was performed as described above. With the exception of the electrolyte, the same bath chemistry was used for both adsorption and electrolytic grafting. The concentration of B-PEI-1 in the tank was about 1.25% by weight. It has been found that a 1.25 wt% B-PEI-1 concentration generally gives the best results for electrografting. The increase in polymer concentration did not appear to result in an increase in nitrogen concentration on the fiber surface. The tank was non-aqueous and MEOH was used. For the electrografting, the vessel contained TEABF as the supporting electrolyte. The carbon fiber tow was exposed to the bath for 1-2 minutes. The carbon fibers were then evaluated using XPS to determine the atomic concentration percent of carbon (C), nitrogen (N) and oxygen (O). The control carbon fiber tow was not subjected to tank treatment. The results are summarized in Table 1 below.

  Adsorption methods, also known as “wet chemistry” techniques, utilize the reaction of fibers with organic molecules containing multiple amine functional groups. In general, amines are believed to react with surface functional groups on the carbon fiber, such as carboxylic acids (which produce salts and / or amides) or others, resulting in the adsorption of the polymer onto the carbon fiber. From the results in Table 1, it can be seen that the adsorption method yields significantly lower concentrations of amine groups (as evidenced by the nitrogen atom concentration) on the surface of the composite carbon fiber. Furthermore, even though B-PEI-1 can be immobilized on carbon fibers by simple adsorption from organic solutions, in many cases this type of deposit has been found to be very heterogeneous. . As shown in Table 1, the XPS results are irreproducible, some samples show varying degrees of nitrogen surface concentration increase, and some are relatively relative to the control carbon fiber (Control 1). There was no increase (eg, comparison 2).

  In contrast, the electrografted carbon fiber is found to be very reproducible, and the electrograft of B-PEI-1 is much more homogeneous on the carbon fiber surface compared to the adsorption technique. Has been suggested. It was also confirmed that only half the period (1 minute vs. 2 minutes) was required to introduce a higher nitrogen surface concentration than the best case of adsorbed B-PEI-1.

  In the following examples, various composite fibers were prepared by electrografting an amine functionalized polymer onto carbon fibers as described above. Subsequently, the obtained composite carbon fiber was used to produce a laminated panel as described above.

Example 3: Electrografting of B-PEI-1 onto IM-7 carbon fiber tow

A bath containing a 20 mM solution of tetraethylammonium tetrafluoroborate as supporting electrolyte (SE) in MeOH and 1.25 wt% B-PEI-1 was prepared. B-PEI-1 was electrografted onto IM-7 carbon fiber tow according to the procedure described above. A laminated panel was produced using the obtained composite carbon fiber and epoxy resin. Next, the interlayer strength of the laminated panel was evaluated using the SBS test. The results are summarized in Table 2 below.

  As can be seen in Table 2, XPS analysis showed a significant increase in nitrogen surface concentration compared to the control fiber (ie, Control 2). In particular, Table 2 shows that the electrografted carbon fiber (Example 3) exhibited an increase in surface nitrogen concentration of 192.7% compared to the control carbon fiber. This nitrogen concentration remained unchanged during prolonged sonication in methanol (30 minutes), indicating that B-PEI-1 was covalently bound to the surface of the carbon fiber. Electrografted carbon fibers also contained trace amounts of fluorine and boron from the supporting electrolyte, which were easily removed by sonication.

  Furthermore, laminated panels made from composite carbon fibers also showed improved interlayer strength as evidenced by the SBS results shown in Table 2. As shown, the laminate made from the composite carbon fiber of Example 3 showed an increase in interlayer strength of over 7% over the control fiber.

Example 4: SBS evaluation of laminates made using electrolytic grafting of branched PEI on IM-7 12K fiber tow and BMI resin

In this example, a laminated panel was produced using the composite carbon fiber of Example 3 and a BMI resin. Similar to Example 3, the upper panel was evaluated with SBS. The results are summarized in Table 3 below.

  Similar to Example 4, the laminate prepared using the composite carbon fiber showed improved interlayer strength compared to the laminate made from the control carbon fiber. The laminate made from the composite carbon fiber in Example 3 showed an almost 10% increase in interlayer strength compared to the control fiber.

Comparative Examples 4 and 5: SBS evaluation of laminates prepared using electrolytic grafting of tris (2-aminoethyl) amine (TAEA) onto IM-7 12K fiber tow and epoxy (EPOXY) resin

In Comparative Examples 4 and 5, composite carbon fiber was produced by grafting TAEA onto the surface of the carbon fiber. Next, a laminated panel was prepared using an epoxy (EPOXY) resin (Comparative Example 4) or a BMI resin (Comparative Example 5), and evaluated by SBS. A bath containing a 20 mM solution of tetraethylammonium tetrafluoroborate as a supporting electrolyte (SE) and 1.25 wt% TAEA was prepared. TAEA was electrografted onto IM-7 carbon fiber tow according to the above procedure. Composite carbon fibers were also evaluated using XPS.

  XPS analysis (Table 4) showed a 75.6% increase in surface nitrogen concentration compared to the control fiber. This concentration remained unchanged during prolonged sonication in methanol (30 minutes), indicating that TAEA was covalently bound on the surface. The composite carbon fiber also contained trace amounts of fluorine and boron from the supporting electrolyte, which were removed by sonication.

  The composite carbon fiber showed a moderate increase in nitrogen content due to the TAEA electrografting, but this increase did not lead to an increase in interlaminar strength, as is evident from the SBS results shown in Table 4. . Thus, the importance of using amine functionalized polymers to achieve improved interlayer strength of the laminate can be seen.

Examples 6 and 7: Electrolytic grafting of B-PEI-2 onto IM-7 12K fiber tow and SBS evaluation of laminates made using BMI and epoxy (EPOXY) resin

In this example, composite carbon fiber was produced using B-PEI-2. B-PEI-2 has a weight average molecular weight of about 800. Composite carbon fibers were made as described in Example 3 and evaluated by XPS. Laminated panels were also made using epoxy (EPOXY) resin and BMI resin and then evaluated by SBS. The results are summarized in Table 5 below.

  XPS analysis from Table 5 showed a 126.8% increase in surface nitrogen concentration compared to the control fiber. This increase in nitrogen concentration was small compared to high molecular weight polymer electrografting (see, eg, Example 3 above). The nitrogen concentration remained unchanged during prolonged sonication in methanol (30 minutes), indicating that B-PEI-2 was covalently bonded onto the carbon fiber surface. The grafted fibers also contained traces of fluorine and boron from the supporting electrolyte, which were removed by sonication.

  SBS data showed a negligible increase in interlayer strength for both the epoxy (EPOXY) laminate panel (Example 6) and the BMI laminate panel (Example 7) compared to the control carbon fiber. From Table 5, it can be seen that the low molecular weight PEI did not statistically improve the interlaminar strength properties of the laminated panels.

Example 8: SBS evaluation of an electrograft of branched B-PEI-1 onto an IMU 12K fiber tow and a laminate made of BMI resin

In the following examples, the interlaminar strength properties of laminates containing electrografted IMU carbon fibers (untreated 12,000 filament tows) were evaluated. By passing IMU carbon fiber through a bath containing a 20 mM MeOH solution of tetraethylammonium tetrafluoroborate supporting electrolyte (SE) containing 1.25 wt% branched B-PEI-1, composite carbon is obtained. Fibers were made. The composite carbon fiber was evaluated by XPS. The laminated panel was made of composite carbon fiber and BMI resin. The laminated panel was evaluated by SBS. The results are summarized in Table 6 below.

  The XPS analysis in Table 6 showed a significant increase in nitrogen concentration when compared to the control 8 carbon fiber. In particular, the electrografted carbon fiber of Example 8 showed a 495.5% increase in surface nitrogen concentration compared to the control carbon fiber. This concentration remained unchanged upon prolonged sonication in methanol (30 minutes), indicating that B-PEI-1 was covalently bonded onto the carbon fiber surface. The electrografted fiber also contained trace amounts of fluorine and boron from the supporting electrolyte, which could be removed by sonication.

  Furthermore, the electrografted fiber (Example 8) was found to have a fairly significant increase in oxygen surface concentration compared to the previous example. This phenomenon is thought to be due to the presence of water in the reagents (especially PEI) and the reactivity of the IMU fiber surface itself, which cannot be completely removed using anhydrous solvents. Also, the formation of a small amount of carbonaceous precipitate was observed at the end of all IMU runs in the electrolytic bath. This may be the result of multiple unidentified processes occurring simultaneously on the IMU fiber surface. Even during a blank run (without PEI or TAEA), some surface etching and surface oxidation appeared to have occurred.

  In response to this result, a blank run was made in which the tank did not contain any polymer (Control 9). The control 9 carbon fiber was found to have some increase in oxygen, most likely due to the presence of water in the electrograft. As a result, it was decided to compare the SBS data of Example 8 and Control 9. SBS data for the control 8 fiber was not evaluated. As can be seen, the untreated IMU carbon fiber also showed improved interlayer strength compared to the control 9 carbon fiber. In this case, the composite carbon fiber of the present invention showed almost 23% improvement in SBS compared to Control 9.

  It should be noted that due to the above complex situation, a clear interpretation of the results of the above example in Table 6 is difficult. In all cases of IMU fibers, the observed SBS strength is the SBS of a laminate composed of grafted IM-7 fibers and feed IM-7 fibers (both electrochemically processed by standard methods). Much lower than strength. This is an interesting observation because both IM-7 and IMU graft fibers appear to have similar amounts of graft PEI or TAEA (XPS). This result seems to emphasize the importance of the surface topology (roughness) of the fibers.

Comparative Example 6: Evaluation of laminate produced using electrolytic graft of TAEA on IMU 12K fiber tow and BMI resin

In this example, TAEA was electrografted onto untreated IMU carbon fiber. Using the obtained composite fiber, a laminate with a BMI resin was produced. Composite carbon fibers and laminated panels were evaluated by XPS and SBS, respectively. The results are summarized in Table 7 below.

  XPS analysis (Table 7) showed a 177.3% increase in surface nitrogen concentration compared to the control fiber. This concentration remained unchanged during prolonged sonication in methanol (30 minutes), indicating that TAEA was covalently bound on the surface. The electrografted fiber also contained traces of fluorine and boron from the supporting electrolyte, which were removed by sonication. As in the previous example, an increase in oxygen surface concentration was observed in the electrografted fiber, and therefore a blank (not containing TAEA in the vessel) was made. Blank carbon fiber (Control 10) was found to have some increase in oxygen, which is most likely due to the presence of water in the electrograft. Comparative Example 6 and Control Fiber 9 were evaluated for SBS. The results are summarized in Table 7 above. Although the TAEA graft fiber showed a 10% increase in SBS, the improvement of the PEI grafted carbon fiber (Example 8) was much more significant. Both examples (Example 8 and Comparative Example 5) used the same controls.

  In the following examples, composite carbon fibers in which carbon fibers include IM-X carbon fibers were produced. Similarly to the previous example, the composite carbon fiber was evaluated by XPS, and the laminated panel produced therefrom was evaluated by SBS.

Examples 9 and 10: SBS evaluation of B-PEI-1 electrolytic grafting onto IM-X untreated 12K fiber tows and laminates made using BMI and epoxy (EPOXY) resin

  In this example, composite carbon fibers were made using B-PEI-1 and IM-X carbon fibers. Composite carbon fibers were made as described in Example 3 and evaluated by XPS. Specifically, a tank containing a 20 mM MeOH solution of tetraethylammonium tetrafluoroborate supporting electrolyte (SE) and 1.25 wt% B-PEI-1 was prepared. A composite carbon fiber was prepared as described above. The fibers were then evaluated by XPS. The results are summarized in Table 8 below. As can be seen in Table 8, the electrografted carbon fibers had a 53.2% increase in surface N concentration compared to the control carbon fibers.

Laminate panels were also made using epoxy (EPOXY) (Example 9) resin and BMI (Example 10) resin and then evaluated by SBS. The results for XPS and SBS evaluation are summarized in Table 8 below.

  For the epoxy based laminate (Example 9), the SBS results showed a 12% improvement in interlaminar strength compared to the laminate made from the control carbon fiber. The BMI-based laminate (Example 10) showed an improvement in interlayer strength of over 45.9% compared to the laminate made from the control carbon fiber.

Examples 11 and 12: Aqueous electrografting of branched B-PEI-1 onto IM-X untreated 12K fiber tow and evaluation of laminates made with epoxy (EPOXY) resin and BMI resin

A bath of 0.5M aqueous solution of sodium sulfate supporting electrolyte (SE) and 1.25 wt% branched B-PEI-1 was prepared. B-PEI-1 was electrolytically grafted onto carbon fibers by the method and conditions described above. “Blank run” fibers (Control 13 and Control 15) were also made in which the tank contained no polymer. Using the obtained carbon fiber, a laminated panel containing an epoxy (EPOXY) resin (Example 11) and a BMI resin (Example 12) was produced. As described above, composite carbon fibers and laminated panels were evaluated by XPS and SBS, respectively. The results are summarized in Table 9 below. As can be seen in Table 9, the electrografted carbon fibers had an increase in N surface concentration of 106.5% compared to the control carbon fibers (Control 12).

  The aqueous graft was somewhat more complicated. Like IMU (untreated surface) fibers, and unlike IM-7 (100% surface treated), IM-X fibers are easier to modify, as determined by XPS analysis of “blank run” fibers. Clearly (Controls 13 and 15). A very significant change in surface chemistry was observed, i.e. an almost 2-fold increase in O concentration. Therefore, “blank run” fibers were produced for comparison of SBS properties exactly as in the case of IMU fibers. This addition was considered correct because an improvement in SBS properties was observed in laminates comprised of “blank run” fibers when compared to laminates from the feed fibers. This result is believed to be due to the additional surface treatment of the IM-X feed fiber in aqueous blank conditions. However, PEI (water-based) grafted fibers are much more significant than “Blank Run” fibers in SBS properties when compared to the original IM-X 12K fibers and when compared to each other in both epoxy and BMI composites. Still showed an increase.

  From Table 9, an aqueous electro-grafting of B-PEI-1 onto carbon fibers was made using a 106.5% increase in nitrogen concentration on the fiber surface and composite carbon fibers compared to Control-12. It can be seen that the interlayer strength of the laminated panel increases. In particular, a laminated panel composed of epoxy (EPOXY) (Example 11) showed an increase in interlaminar strength of over 16% compared to the control fiber (Control 12). Similarly, the BMI-based laminate panel (Example 12) showed an increase in interlaminar strength of greater than 59% compared to the control fiber (Control-14).

Examples 13 and 14: Electrografting of linear PAH onto IM-7 treated 12K fiber tows and evaluation of laminates made with epoxy (EPOXY) resin and BMI resin

In this example, an electrograft using PAH as the amine functionalized polymer was evaluated. A bath of tetraethylammonium tetrafluoroborate supporting electrolyte (SE) in 20 mM MeOH and 1.25 wt% PAH was prepared. PAH was electrografted onto IM-7 12,000 filament tow according to the above procedure. With the obtained carbon fiber, a laminated panel containing an epoxy (EPOXY) resin and a BMI resin was produced. As described above, composite carbon fibers and laminated panels were evaluated by XPS and SBS, respectively. The results are summarized in Table 10 below.

  From Table 10, it can be seen that the electrografting of PAH onto carbon fiber results in a 60.3% increase in nitrogen concentration on the surface of the carbon fiber compared to the control carbon fiber. In addition, the electrografting of PAH onto carbon fibers also resulted in increased interlayer strength of laminated panels made using composite carbon fibers. In particular, a laminated panel constructed with epoxy (EPOXY) (Example 13) showed an increase in interlaminar strength of over 5% compared to the control fiber (Control 16). Similarly, the BMI-based laminate panel (Example 14) showed an increase in interlayer strength of over 12% compared to the control fiber (Control 17).

Example 15: Electrolytic grafting of L-PEI onto IM-7 12K fiber tow and evaluation of laminates made with epoxy (EPOXY) resin

In this example, an electrograft using L-PEI as the amine functionalized polymer was evaluated. A bath of tetraethylammonium tetrafluoroborate supporting electrolyte (SE) in 20 mM MEOH and 1.25 wt% L-PEI was prepared. L-PEI was electrografted onto IM-7 12,000 filament tow according to the above procedure. The obtained carbon fiber was prepared into a laminated panel containing an epoxy (EPOXY) resin. As described above, composite carbon fibers and laminated panels were evaluated by XPS and SBS, respectively. The results are summarized in Table 11 below.

  From Table 11, it can be seen that the electrolytic grafting of L-PEI onto carbon fibers results in an increase in the nitrogen concentration on the surface of the fibers, as well as an increase in the interlaminar strength of laminated panels made using composite carbon fibers. In particular, the electrografted carbon fiber showed a 55.5% increase in surface nitrogen concentration compared to the control, and the epoxy (EPOXY) -based laminate panel (Example 15) was 6% compared to the control fiber (Control 18). It showed an increase in interlayer strength exceeding%.

  In particular, the polymer had a completely different structure from branched polyethyleneimine (PEI) in that only secondary amine groups were present. Secondary amines were known to electrograft onto substrates, but were less efficient than primary amines. Nevertheless, these types of polymers can be grafted onto the fibers, and in the case of epoxy composites, a clear improvement in interlayer properties has been observed.

Example 16: Spontaneous grafting of B-PEI-1 on IM-7 12K fiber tow and evaluation of laminate made in epoxy (EPOXY) resin

A bath of tetraethylammonium tetrafluoroborate supporting electrolyte (SE) in 20 mM MEOH and 1.25 wt% B-PEI-1 was prepared. B-PEI-1 was grafted onto IM-7 12,000 filament tow by passing the tow through a bath. No voltage was applied to the cell. The obtained carbon fiber was prepared into a laminated panel containing an epoxy (EPOXY) resin. As described above, composite carbon fibers and laminated panels were evaluated by XPS and SBS, respectively. The results are summarized in Table 12 below.

  Surprisingly, the XPS analysis showed a significant increase (76.2%) in surface nitrogen concentration when compared to the control carbon fiber (Control 19). In particular, this increase in concentration was comparable to the increase in concentration in examples where B-PEI-1, L-PEI and PAH were electrografted onto carbon fibers.

  In Example 16, the inventor evaluated the possibility of spontaneous grafting / attachment of amine-containing polymers onto carbon fibers. It is believed that branched PEI can adhere to IM-7 fibers in an amount significantly sufficient to improve the short beam shear strength of laminates obtained with epoxy resins, without any potential applied to the cell. Even if no potential is applied to the cell, a potential of 0.7-0.8 V is usually measured on the fiber (open circuit potential), especially primary amines (usually 1.5 for primary amino groups). In the case of PEI containing secondary and tertiary amino groups that are known to generate radical cations at potentials lower than the range of ~ 1.6V, this potential generates cation radicals. It should be noted that this may be sufficient. Some have reported that spontaneous grafting of amines is much less efficient than typical electrolytic grafting. However, so far only "small" molecules have been studied, and for "large" polymer molecules it may not be necessary to form many bonds with the fiber surface to introduce more functional groups on the surface. It must be pointed out that there is no. Thus, as shown in secondary amines (Example 15) and spontaneous grafts (Example 16), amine functional groups are sufficient for further reaction with the resin matrix and improved interlayer properties, even for low efficiency grafts. May be sufficient to introduce.

Example 17: Grafting of B-PEI-1 onto HM-63 12K fiber tow and evaluation of laminate made with epoxy (EPOXY) resin

In this example, an electrograft using B-PEI-1 as the amine functionalized polymer was evaluated. A bath of tetraethylammonium tetrafluoroborate supporting electrolyte (SE) in 20 mM MEOH and 1.25 wt% B-PEI-1 was prepared. B-PEI-1 was electrografted onto HM-63 12,000 filament tow according to the above procedure. The obtained carbon fiber was prepared into a laminated panel containing an epoxy (EPOXY) resin. As described above, composite carbon fibers and laminated panels were evaluated by XPS and SBS, respectively. The results are summarized in Table 13 below.

  From Table 13, it can be seen that the electrografting of B-PEI-1 onto carbon fibers results in an increase in the nitrogen concentration on the surface of the fiber and an increase in the interlayer strength of the laminated panel made with the composite carbon fiber. . In particular, the electrografted carbon fiber exhibits an increase in surface nitrogen concentration of 2,900%, and the epoxy (EPOXY) based laminate panel (Example 17) has an interlaminar strength of greater than 5% compared to the control fiber (Control 20). Showed an increase.

Summary of claims

  1. A composite carbon fiber comprising carbon fiber electrografted with an amine functionalized polymer on a surface.

  2. The composite carbon fiber of claim 1, wherein the composite carbon fiber has a nitrogen / carbon (N / C) ratio of at least 0.125.

  3. The composite carbon fiber of claim 1, wherein the composite carbon fiber has an N / C ratio of at least 0.150.

  4). The composite carbon fiber according to claim 1, wherein the composite carbon fiber has an N / C ratio of about 0.15 to 0.3.

  5. The composite carbon fiber according to claim 1, wherein the composite carbon fiber has an N / C ratio of about 0.15 to 0.2.

  6). 6. The composite carbon fiber according to any one of the preceding claims, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is at least 50% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. The composite carbon fiber according to item or above.

  7). 7. The composite carbon fiber according to any one of claims 1 to 6, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is at least 75% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. The composite carbon fiber according to item or above.

  8). 8. The composite carbon fiber according to any one of claims 1 to 7, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is at least 100% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. The composite carbon fiber according to item or above.

  9. 9. The composite carbon fiber according to any one of claims 1 to 8, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is at least 125% compared to the original carbon fiber on which no amine-functionalized polymer has been electrografted. The composite carbon fiber according to item or above.

  10. The composite carbon fiber has a nitrogen surface concentration that is at least 150%, such as at least 175%, at least 200% or at least 250% compared to the original carbon fiber on which no amine-functionalized polymer has been electrografted. The composite carbon fiber according to claim 1, which exhibits an increase.

  11. 11. The composite carbon fiber according to any one of the preceding claims, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is at least 495% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. The composite carbon fiber according to item or above.

  12 12. The composite carbon fiber according to any of claims 1 to 11, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is about 50-500% compared to the original carbon fiber on which no amine functionalized polymer is electrografted. The composite carbon fiber according to claim 1 or more.

  13. 13. The composite carbon fiber of any of claims 1-12, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is about 100-500% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. The composite carbon fiber according to claim 1 or more.

  14 14. The composite carbon fiber according to any of claims 1 to 13, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is about 150-500% compared to the original carbon fiber on which no amine functionalized polymer is electrografted. The composite carbon fiber according to claim 1 or more.

  15. 15. The composite carbon fiber according to any one of claims 1 to 14, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is about 200-500% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. The composite carbon fiber according to claim 1 or more.

  16. 16. The composite carbon fiber according to any one of claims 1 to 15, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is about 100-250% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. The composite carbon fiber according to claim 1 or more.

  17. 17. The composite carbon fiber of any of claims 1-16, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is about 125-200% as compared to the original carbon fiber that has not been electrografted with an amine functionalized polymer on the surface. The composite carbon fiber according to claim 1 or more.

  18. The amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, poly (allylamine). 18. One or more of claims 1 to 17 selected from the group consisting of branched poly (allylamine) (PAADVB) and block copolymers, core-shell particles and combinations thereof prepared by branching with divinylbenzene. The composite carbon fiber described in 1.

  19. 19. Composite carbon fiber according to any one or more of claims 1 to 18, wherein the amine functionalized polymer comprises branched polyethyleneimine.

  20. The composite carbon fiber according to claim 1, wherein the carbon fiber has a tensile strength of at least 400 ksi.

  21. 21. The composite carbon fiber according to any one or more of claims 1 to 20, wherein the carbon fiber has a tensile strength of about 600 to 1,050 ksi.

  22. 22. The composite carbon fiber according to any one or more of claims 1-21, wherein the amine functionalized polymer has a weight average molecular weight ranging from about 5,000 to 35,000.

  23. A fiber-reinforced composite material comprising the composite carbon fiber according to any one of claims 1 to 22.

  24. A fiber reinforced composite material comprising carbon fibers electrografted with an amine functionalized polymer on the surface and a resin matrix injected into said carbon fibers, as characterized by a short beam shear (SBS) test, about 17 Fiber reinforced composite material showing interlaminar strength of ˜25 ksi.

  25. 25. The fiber reinforced composite material of claim 24, wherein the interlaminar strength of the fiber reinforced composite material is about 20-22 ksi as characterized by SBS.

  26. The fiber reinforced composite material is in the range of about 5-25% compared to a similar fiber reinforced composite material, wherein the carbon fiber is the same except that the surface of the carbon fiber does not contain an amine functionalized polymer. 26. A fiber reinforced composite material according to claim 24 or 25, which exhibits an increase in SBS over.

  27. 27. The fiber reinforced composite material according to any one of claims 24 to 26, wherein the surface of the composite carbon fiber has a nitrogen / carbon (N / C) ratio of about 0.15 to 0.3.

  28. 28. The fiber-reinforced composite material according to claim 24, wherein the resin is selected from the group consisting of an epoxy resin, a bismaleimide resin, a cyanate ester resin, and a phenol resin.

  29. 29. A fiber reinforced composite material according to any one or more of claims 24 to 28, wherein the carbon fibers have a tensile strength of about 600 to 1,050 ksi.

  30. The amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, poly (allylamine). 30. A fiber reinforced composite material according to any one or more of claims 24 to 29, selected from the group consisting of branched poly (allylamine) (PAADVB) prepared by branching with divinylbenzene and combinations thereof.

  31. 31. A fiber reinforced composite material according to any one or more of claims 24 to 30, wherein the amine functionalized polymer comprises branched polyethyleneimine.

  32. The composite carbon fiber is at least 25%, at least 50%, at least 75%, at least 100%, at least 125%, at least 150% compared to the original carbon fiber on which no amine functionalized polymer is electrografted. %, At least 175%, at least 200%, at least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, at least 450%, 32. A fiber-reinforced composite material according to any one or more of claims 24-31, which exhibits an increase in the surface of any one or more nitrogen concentrations of at least 475% or at least 500%.

  33. The composite carbon fiber is about 50-3,000%, such as about 100-500%, about 150-500%, about 150% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface. 32. A fiber-reinforced composite material according to any one or more of claims 24-31, showing an increase in the surface of nitrogen concentration ranging from 100-250% or about 125-200%. 34. An aerospace component comprising the fiber-reinforced composite material according to any one of claims 24-33.

35. A composite carbon fiber comprising carbon fibers electrografted with an amine functionalized polymer on a surface,
a) a nitrogen / carbon (N / C) ratio that is at least 0.125, and / or b) as compared to the original carbon fiber that is not electrografted with an amine-functionalized polymer on the surface of the carbon fiber. A composite carbon fiber characterized by an increase in nitrogen surface concentration of 50-3,000%.

  36. 36. The composite carbon fiber exhibits a nitrogen / carbon (N / C) ratio that is about 0.15 to 0.3, such as about 0.15 to 0.2 and about 0.165 to 0.195. The composite carbon fiber described in 1.

  37. The composite carbon fiber is at least 75%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200, as compared to the original carbon fiber on which no amine functionalized polymer is electrografted. %, At least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, at least 450%, at least 475% or at least 500% 37. A composite carbon fiber according to claim 35 or 36, which exhibits an increase in the surface of any one or more nitrogen concentrations.

  38. The composite carbon fiber is about 50-500%, such as about 100-500%, about 150-500%, about 100-500% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface. 38. A composite carbon fiber according to any one or more of claims 35 to 37, which shows an increase in the surface of the nitrogen concentration ranging from 250% or about 125 to 200%.

  39. The amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, poly (allylamine). 39. The composite carbon fiber according to any one of claims 35 to 38, selected from the group consisting of branched poly (allylamine) (PAADVB) prepared by branching with divinylbenzene and combinations thereof.

  40. 40. The composite carbon fiber of any one of claims 35 to 39, wherein the amine functionalized polymer comprises branched polyethyleneimine.

  41. 41. The composite carbon fiber according to any one of claims 35 to 40, wherein the carbon fiber has a tensile strength of at least 400 ksi.

  42. 42. The composite carbon fiber according to any one of claims 35 to 41, wherein the carbon fiber has a tensile strength of about 600 to 1,050 ksi.

  43. 43. The composite carbon fiber of any one of claims 35 to 42, wherein the amine functionalized polymer has a weight average molecular weight ranging from about 5,000 to 35,000.

  44. The fiber reinforced composite material containing the composite carbon fiber as described in any one of Claims 35-43.

  45. 45. A method of making a composite carbon fiber according to any one of claims 1-44, wherein the carbon fiber is passed through a bath containing an amine functionalized polymer, an electric potential is applied to the cell, and the amine. Electrografting a functionalized polymer onto the carbon fiber to produce a composite carbon fiber having an amine functionalized polymer electrografted on the surface.

  46. A method of making a composite carbon fiber comprising passing a carbon fiber through a bath containing an amine functionalized polymer, applying a potential to a cell, and electrografting the amine functionalized polymer onto the carbon fiber. Producing a composite carbon fiber having an electrofunctionalized amine functionalized polymer on the surface, wherein the composite carbon fiber is a) at least 0.125 nitrogen / carbon (N / C) ratio, and / or b ) A method characterized by an increase in nitrogen surface concentration that is about 50-500% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface of the carbon fiber.

  47. 49. The composite carbon fiber exhibits a carbon / nitrogen (N / C) ratio that is about 0.15-0.3, such as about 0.15-0.2 and about 0.165-0.195. The method described.

  48. The composite carbon fiber is at least 75%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200, as compared to the original carbon fiber on which no amine functionalized polymer is electrografted. %, At least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, at least 450%, at least 475% or at least 500% 48. The method of claim 46 or 47, wherein the method shows an increase in the surface of any one or more nitrogen concentrations.

  49. The composite carbon fiber is about 50-3,000%, such as about 100-500%, about 150-500%, about 150% compared to the original carbon fiber where the amine functionalized polymer is not electrografted on the surface. 49. A method according to any one or more of claims 46 to 48, which shows an increase in the surface of the nitrogen concentration ranging from 100 to 250% or about 125 to 200%.

  50. The amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, poly (allylamine). 50. A method according to any one or more of claims 46 to 49, selected from the group consisting of branched poly (allylamine) (PAADVB) prepared by branching with divinylbenzene and combinations thereof.

  51. 51. The method of any one or more of claims 46-50, wherein the amine functionalized polymer comprises branched polyethyleneimine.

  52. 52. A method according to any one or more of claims 46 to 51, wherein the carbon fibers have a tensile strength of at least 400 ksi.

  53. 53. A method according to any one or more of claims 46 to 52, wherein the carbon fibers have a tensile strength of about 600 to 1,050 ksi.

  54. 54. The method of any one or more of claims 46-53, wherein the amine functionalized polymer has a weight average molecular weight ranging from about 5,000 to 35,000.

  55. 55. A method according to any one or more of claims 46 to 54, wherein the step of electrografting the amine functionalized polymer onto the carbon fibers continues for a period of 30 seconds to 2 minutes.

56. 55. A method according to any one or more of claims 46 to 54, wherein the step of electrografting the amine functionalized polymer onto the carbon fibers continues for a period of 45 seconds to 90 seconds.

Claims (21)

  A composite carbon fiber comprising carbon fiber electrografted with an amine functionalized polymer on a surface.   Nitrogen / carbon (N / N) wherein the composite carbon fiber is at least 0.125, preferably at least 0.150, more preferably about 0.15-0.3, even more preferably about 0.15-0.2. The composite carbon fiber according to claim 1, having a C) ratio.   The composite carbon fiber is at least 50%, at least 75%, at least 100%, at least 125%, at least 150%, at least 175 compared to the original carbon fiber on which no amine functionalized polymer is electrografted. Composite carbon fiber according to claim 1 or 2, exhibiting an increase in nitrogen surface concentration that is%, at least 200% and / or at least 250%.   4. The composite carbon fiber according to any of claims 1 to 3, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is at least 495% compared to the original carbon fiber on which no amine-functionalized polymer is electrografted. The composite carbon fiber described.   5. The composite carbon fiber according to any of claims 1 to 4, wherein the composite carbon fiber exhibits an increase in nitrogen surface concentration that is about 50-500% compared to the original carbon fiber that is not electrografted with an amine functionalized polymer on the surface. A composite carbon fiber according to claim 1.   The composite carbon fiber is about 100-500%, especially about 150-500%, about 200-500%, about 100-500% compared to the original carbon fiber where the amine-functionalized polymer is not electrografted on the surface. 6. The composite carbon fiber according to any of claims 1-5, exhibiting an increase in nitrogen surface concentration that is 250% and / or about 125-200%.   The amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, poly (allylamine). 7. A branched poly (allylamine) (PAADVB) and block copolymer prepared by branching with divinylbenzene, selected from the group consisting of block copolymers, core-shell particles and combinations thereof. Composite carbon fiber.   The composite carbon fiber of any of claims 1-7, wherein the amine functionalized polymer comprises branched polyethyleneimine.   The composite carbon fiber according to any one of claims 1 to 8, wherein the carbon fiber has a tensile strength of at least 400 ksi, such as a tensile strength of about 600 to 1,050 ksi.   10. The composite carbon fiber of any of claims 1-9, wherein the amine functionalized polymer has a weight average molecular weight ranging from about 5,000 to 35,000.   The fiber reinforced composite material containing the composite carbon fiber in any one of Claims 1-10.   A fiber reinforced composite material comprising carbon fibers electrografted with an amine functionalized polymer on the surface and a resin matrix injected into said carbon fibers, as characterized by a short beam shear (SBS) test, about 17 Fiber reinforced composite material exhibiting an interlaminar strength of ˜25 ksi and in particular 20-22 ksi.   The fiber reinforced composite material is in the range of about 5-25% compared to a similar fiber reinforced composite material, wherein the carbon fiber is the same except that the surface of the carbon fiber does not contain an amine functionalized polymer. 13. A fiber reinforced composite material according to claim 11 or 12, which exhibits an increase in SBS up to.   The fiber reinforced composite material according to any of claims 11 to 13, wherein the surface of the composite carbon fiber has a nitrogen / carbon (N / C) ratio of about 0.15 to 0.3.   The fiber-reinforced composite material according to any one of claims 12 to 14, wherein the resin is selected from the group consisting of an epoxy resin, a bismaleimide resin, a cyanate ester resin, and a phenol resin.   16. A fiber reinforced composite material according to any of claims 12 to 15, wherein the carbon fibers have a tensile strength of about 600 to 1,050 ksi.   The amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, poly (allylamine). 17. A fiber-reinforced composite material according to any of claims 12 to 16, selected from the group consisting of branched poly (allylamine) (PAADVB) prepared by branching with divinylbenzene and combinations thereof. A method for producing a composite carbon fiber according to any one of claims 1 to 17,
Passing carbon fibers through a bath containing an amine functionalized polymer;
Applying a potential to the cell; and electrografting the amine functionalized polymer onto the carbon fiber to produce a composite carbon fiber having an amine functionalized polymer electrografted on the surface;
And the composite carbon fiber is characterized by:   19. The composite carbon fiber exhibits a carbon / nitrogen (N / C) ratio that is about 0.15-0.3, such as about 0.15-0.2 and about 0.165-0.195. The method described.   The amine functionalized polymer comprises linear polyethyleneimine (PEI), branched polyethyleneimine (PEI), branched polypropyleneimine, linear poly (allylamine) (PAA), polyamidoamine (PAMAM) dendrimer, poly (allylamine). 20. A process according to any of claims 18 or 19 selected from the group consisting of branched poly (allylamine) prepared by branching with divinylbenzene (PAADVB) and combinations thereof. 21. A method according to any of claims 18 to 20, wherein the step of electrografting the amine functionalized polymer onto the carbon fibers continues for a period of 30 seconds to 2 minutes and in particular for a period of 45 seconds to 90 seconds. .